Refining white metal scrap



Patented Oct. 9, 1934 1,976,225 BEFINING WHITE METAL SCRAP George 0.fliers, Brooklyn, N. Y., assignor to National Lead Company, New York, N.Y., a corporation of New Jersey No Drawing. Application July 19, 1930,Serial No. 469,254

3 Claims. (01. 75-15) The invention relates to the refining or treatingof white metal or tinor lead-base alloys for the purpose of separatingtherefrom certain ingredient metals regarded as undesirable or as 5impurities and commonly such as antimony, copper, arsenic and iron, andmore particularly, to the recovery of such impurity metals from the mushproduced by mixing aluminum with such white metal alloys according tothe process described and claimed in a companion application by WilliamA. Cowan, Serial No. 469,251, filed July 19, 1930.

The process referred to is briefly as follows:

The existing relative proportion of the impurity metal or metals presentin the alloy to be treated is first ascertained and then there is addedthereto or combined therewith, while in a molten state,

a predetermined quantityof aluminum and vigorously stirred therein, thetemperature being raised to the point where such aluminum reacts withthe impurity metal or metals. The reaction results in the formation ofdefinite chemical compounds of aluminum with such impurity metal ormetals as may be present, having a composition corresponding closely tothe generalformulas AlSb and AlClla etc. After the aluminum reaction,the metal is allowed to cool to a point below that at which the bulk ofaluminum compounds referred to are soluble therein, about 3: 300 C.,which causes all ofthe products of the reaction between the aluminum andthe impurity metal or metals to collect and float high upon the moltenmass in the form of a thick mush. This mush is then separated from theliquid met- 35 al, gravitationally, in a filter, or by mixing a dryingagent therein, or otherwise to remove therefrom the excess, or as muchas possible, of the original liquid metal which wets the mush particles,and after such separation, the mush represents the principal by-productof the process referred to.

According to this invention the metallic values of such by-product arerecovered by smelting it, preferably in a reverberatory furnace, incontact 5' with metallic oxides or sulphides, preferably the oxides orsulphides of one or more of the metals already present in the mushmaterial, other than aluminum. According to the character of theoriginal white metal alloy, there may be one or o more of the impuritymetals such as Sb, As, Cu or Fe in the mush material, accompanied bymore or less of the lead or tin from which the mush was filtered orseparated. The smelting operation is exothermic and results in thereduction of the added metallic oxide to metallic form, breakof lead,tin, and antimony added to lead, has a market value.

ing up the mush material into aluminum oxide and metallic antimony,copper, arsenic, etc. as the case may be, and according to the generalreaction illustrated by the foll MO being used in these equatio of theadded metallic oxide and to represent the oxide of the particular metalused for the purpose:

owing equations; us as the symbol being understood it being understoodthat if other impurity metalsare in the by-product they will, inthereaction according On removal of the aluminum of course, appear to thesame principle.

bearing slag the remaining product metal is ready for furthermanufacture or sale according to its composition.

Aspecific example of assuming the separated mush the followingcomposition:

60 A1810 10 Sn 30 Pb the process is as followsmaterial to have of theabove there dross containing The materials in charged into areverberatory furnace and smelted therein. The aluminum oxide (A1203)produced with a liberation of heat is removed as slag and the resultantmetal tapped off. The product metal in this case is an alloy cificexample of the process is as ing the separated mush lowing composition:

60 AlSb l0 Sn 30 Pb ('71, 5, 24) which, when Another spefollows,-assummaterial to have the folremoved as matte and the resultant metaltapped off. The product metal in this case is an alloy of lead, tin,which, when added In view of the fact and antimony (71 %--5%-24%) tolead, has a market value.

that the atomic weight of aluminum is 2'1 and of antimony 121.8, it willbe apparent that, roughly speaking, the proportion of aluminum inthemush com pound treated is approximately 12%, and with such minorproportion of aluminum, it will be further apparent that the temperatureof the reaction is sufliciently low to avoid volatilization of the leador other metals in the melt.

I claim:

1. A step in the process of recovering Sb, As, Cu or Fe present asimpurity in tin and leadbase alloys by reacting with aluminum with suchimpurity metal or metals, which consists in separating the aluminumcompound mush produced in said reaction and causing it to react with anoxide or sulphide of one of the metals other than aluminum which arecontained in said mush, at a temperature less than the volatilizingpoint of said metals.

2. The process of recovering Sb, As, Cu or Fe present as impurity in tinand lead-base alloys which comprises reacting with aluminum on suchimpurity metal or metals, eliminating the liquid wetting metal from themush aluminum compound produced in such reaction and heating theresulting dried mush in the presence of an oxide or sulphide of a metalother than aluminum present in said mush, thereby converting to oxide orsulfide the aluminum in said compound without volatilizing said metals.

3. The process of producing a lead alloy rich in antimony out ofsecondarylead containing antimony which consists in stirring aluminuminto said secondary lead to produce therein a mush compound of aluminumand antimony, separating such compound and heating it with an oxide orsulfide of lead to remove the aluminum therefrom and leave the antimonyalloyed with the lead.

GEORGE O. HIERS.

